The invention relates to the field of surveying and to a surveyor's level or transit for use in surveying and method by which surveying calculations may be based on a constant instrument height in reference to a prescribed benchmark despite moving of the tripod to different locations and elevations at a job site.
Prior survey levels and transits have been utilized which mount on the top of a tripod. The conventional surveyor's level is fixed and reads an instrument height on the surveyor's rod at a benchmark. Each time that the tripod is taken down and set up, a new instrument height is read at the benchmark since it is impossible to set the tripod up at the same exact location and elevation. When surveying is begun again, a new set of calculations must then be started with a new instrument height. The prior calculations of the surveyor at the job are lost.
In completing even a small job, a surveyor may make from thirty to several hundred readings. When the surveying instrument is set up, the surveyor first turns to the benchmark and reads the surveyor's rod to get the height of the surveying instrument. He then turns to the job site and makes the numerous readings which are required for the job. These readings are all based on the instrument height as previously determined from the exact location at which the tripod is set. During the day or week while the surveyor is on the job it becomes necessary for the tripod including level to be moved and set back up frequently. Each time that the surveyor's level is set back up there is a new instrument height since the tripod cannot be set back up in the same exact location. This means that the surveyor must start a new set of calculations for the numerous readings he must make on the site based on the new instrument height. All of the previous grade readings and calculations read by the surveyor before he moved the surveying level are lost. He must now start a new set of calculations and grade readings depending on the new instrument height of the survey level. It is typical for an engineer to have several pages of grade readings at the end of each day's work which are lost when he begins the next day's work and the instrument is set back up. All of this can become very time consuming and tedious work, often frustrating the surveyor if the tripod has to be moved frequently.
Even minor situations such as taking a lunch break or moving the surveyor's level to allow a truck to pass by require that a new instrument height and new calculations be made.
Accordingly, an object of the invention is to provide a surveyor's level and method by which grade readings and calculations on a job are not lost when the tripod is moved to a new location and elevation.
Another object of the invention is to provide a surveyor's level which may set at the same instrument height each time the tripod is moved.
Still another object of the invention is to provide a surveyor's level which is elevatable and adjustable on a tripod so that it may be set in reference to a benchmark at a desired instrument height and reset to that same exact instrument height even after the level has been taken down and set back up at different locations and elevations at the job site.
Still another object of the invention is to provide a survyor's level which may be adjusted in its vertical position to follow successive courses of brick or other building block material to determine if the mortar joint between the courses is level. Often the mortar joint becomes off-grade so that the walls become unlevel and the bricks at the various intersecting walls do not match up with each other.